ABSTRACT
Within a short time after the outbreak of coronavirus disease 2019 (COVID-19) in Wuhan, Hubei, the Chinese government introduced a nationwide lockdown to prevent the spread of the pandemic. The quarantine measures have significantly decreased the anthropogenic activities, thus improving air quality. To study the impacts caused by the lockdown on specific source sectors and regions in the Yangtze River Delta (YRD), the Community Multiscale Air Quality (CMAQ) model was used to investigate the changes in source contributions to fine particulate matter (PM2.5) from 23 January to 28 February 2020, based on different emission control cases. Compared to case 1 (without emission reductions), the total PM2.5 mass for case 2 (with emission reductions) decreased by more than 20 % over the entire YRD, and the reduction ratios of its components were 15 %, 16 %, 20 %, 43 %, 34 %, and 35 % in primary organic aerosol (POA), elemental carbon (EC), sulfate, nitrate, ammonium, and secondary organic aerosol (SOA), respectively. The source apportionment results showed that PM2.5 concentrations from transportation decreased by 40 %, while PM2.5 concentrations from the residential and power sectors decreased by less than 10 % due to the lockdown. Although all sources decreased, the relative contribution changed differently. Contributions from the residential sector increased by more than 10 % to 35 %, while those in the industrial sector decreased by 33 %. Considering regional transport, the total PM2.5 mass of all regions decreased 20 %–30 % in the YRD, with the largest decreased value of 5.0 µgm-3 in Henan, Hebei, Beijing, and Tianjin (Ha-BTH). In Shanghai, the lower contributions from local emissions and regional transmission (mainly Shandong and Ha-BTH) led to the reduced PM2.5. This study suggests adjustments of control measures for various sources and regions.
ABSTRACT
Safe, economical and effective vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are needed to achieve adequate herd immunity and halt the pandemic. We have constructed a novel SARS-CoV-2 vaccine, CoVac501, which is a self-adjuvanting peptide vaccine conjugated with Toll-like receptor 7 (TLR7) agonists. The vaccine contains two immunodominant peptides screened from receptor-binding domain (RBD) and is fully chemically synthesized. And the vaccine has optimized nanoemulsion formulation, outstanding stability and safety. In non-human primates (NHPs), CoVac501 elicited high and persistent titers of RBD-specific and protective neutralizing antibodies (NAbs), which were also effective to RBD mutations. CoVac501 was found to elicit the increase of memory T cells, antigen-specific CD8 + T cell responses and Th1-biased CD4 + T cell immune responses in NHPs. More importantly, the sera from the immunized NHPs can prevent infection of live SARS-CoV-2 in vitro. One-Sentence Summary A novel SARS-CoV-2 vaccine we developed, CoVac501, which is a fully chemically synthesized and self-adjuvanting peptides conjugated with TLR7 agonists, can induce high-efficient humoral and cellular immune responses against SARS-CoV-2.
Subject(s)
Coronavirus InfectionsABSTRACT
Background: As the outbreak of COVID-19 has caused widespread panic in the general public, it is essential to understand how public sentiment has changed.Methods: In the current study, we continuously tracked online public sentiment through the year 2020 by analyzing emotion reflected on 64,723,242 posts across China’s largest social media platform Sina Weibo.Findings: We found that the pandemic not only affected online public sentiment in the initial outbreak but also induced long-term negative effects even in the aftermath of the successful recovery from the pandemic. The long-term negative effect was not due to the pandemic’s severity either locally or globally, or even the post-pandemic economic recession. Rather, we speculate that the long-term negative effects may have resulted from the prolonged emotional trauma associated with the COVID-19 outbreak.Interpretation: COVID-19 induces long-term negative effects of public sentiments even in the aftermath of the successful recovery from the pandemic. It reminds public health and government administrators of the need to pay heed to public mental health even once the pandemic has concluded.Funding Statement: The Hunan Key Research and Development Project Grant (No. 2020SK2094), the National Key Technologies R&D Program of China Grant (No. 2015BAH22F01), and the National Natural Science Foundation of China Grants (No. 31771209).Declaration of Interests: The authors declare no competing interest.Ethics Approval Statement: The study was approved by the ethics committee of Hunan University and East China Normal University.